JPH0128056B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an impact-resistant rubber-reinforced resin composition, particularly an impact-resistant resin composition suitable for manufacturing refrigerator boxes. When manufacturing a molded product with a complex shape and large development area, such as a synthetic resin refrigerator inner box, by vacuum forming, even with advanced molding technology, variations in thickness depending on the location of the molded product can be resolved. I can't do it,
For this reason, thick synthetic resin plates have been used for such molding. On the other hand, in recent years in the field of molding, it has been common practice to reduce the thickness of synthetic resin plates used for vacuum forming for the purpose of resource conservation and cost reduction. When such thin-walled molded products are used, there is a strong demand for a resin that exhibits less variation in thickness depending on the location of the molded product. In addition, refrigerator boxes have a structure in which an insulating material is interposed between the inner box and the outer box, but in many cases, polyurethane injection foaming method is adopted because urethane foam is excellent as an insulating material. has been done. This construction method not only simplifies the process, but because the thermal conductivity of polyurethane foam is lower than that of glass fiber or polystyrene foam, it is possible to reduce the thickness of the insulation layer, and the It has advantages such as increasing effective volume and saving cooling energy. However, when using this construction method, the synthetic resin inner box comes into contact with isocyanate compounds and polyol compounds, which are the raw material components of polyurethane foam, and fluorocarbon gas used as a blowing agent. The box is chemically attacked by these raw materials and its strength is significantly reduced. In addition, when this construction method is used, the synthetic resin inner box and the polyurethane foam are bonded together, and a hard polyurethane layer with almost no foaming is formed at the interface. Since this polyurethane layer is weak, it easily cracks due to temperature differences or slight impacts, and these cracks act as a notch effect on the synthetic resin inner box, significantly reducing the strength of the inner box. In order to prevent the strength of the synthetic resin inner box that comes into contact with the polyurethane foam from decreasing, water-based rubber latex is applied to the side of the synthetic resin inner box that comes into contact with the polyurethane foam to form a film, and then the polyurethane is injected. Foaming method (Special Publication No. 46-13547)
(No. 1), a method in which the inner box is formed by vacuum forming a plastic composite material coated with a fluoride-resistant hydrocarbon film instead of applying water-based rubber latex (Tokuko Showa).
46-13550), and also contains a lot of acrylonitrile component.
A method has been proposed in which a three-layer ABS sheet is used in which an intermediate layer is made of ABS resin and both sides are made of ABS resin containing a large amount of butadiene (Japanese Patent Laid-Open No. 101882/1982). However, all of these methods have the drawback of complicating the manufacturing process of the refrigerator box and increasing costs. The object of the present invention is to have improved vacuum formability;
In particular, it is an object of the present invention to provide an impact-resistant resin composition which can reduce variations in thickness depending on the location of a molded product and can provide a molded product with less loss of strength due to contact with a polyurethane foam. The impact-resistant resin composition of the present invention comprises a graft polymer in which an aromatic vinyl compound and a vinyl cyanide compound are chemically bonded to a rubbery polymer, and an aromatic vinyl compound/vinyl cyanide compound copolymer,
In a rubber-reinforced resin composition used for manufacturing a vacuum-formed box body in contact with a polyurethane foam layer, [] an aromatic compound based on 100 parts by weight of a rubbery polymer contained in the resin composition at a ratio of 10 to 30% by weight; 70~ for group vinyl compounds and vinyl cyanide compounds
120 parts by weight are chemically bonded, and [] the free aromatic vinyl compound/vinyl cyanide compound copolymer contained as a matrix component in the resin composition has an intrinsic viscosity of 0.65 to
0.80, [] The weight ratio of the aromatic vinyl compound to the vinyl cyanide compound in the resin composition is 2.3 to 3.0.
It is characterized by being in the range of Examples of the rubbery polymer used in the present invention include polybutadiene, acrylonitrile-butadiene copolymer, butadiene-styrene copolymer, polyisoprene, polychloroprene, and ethylene-propylene-diene rubber. Moreover, these can also be used in combination of two or more types. The rubber content in the resin composition is preferably 10% by weight or more from the viewpoint of impact resistance.
The content is preferably 14% by weight or more, and is preferably 30% by weight or less and preferably 25% by weight or less in order to maintain a satisfactory heat deformation temperature and stiffness. Examples of the aromatic vinyl compound used in the present invention include styrene, α-methylstyrene, dimethylstyrene, vinyltoluene, and alkoxystyrene. Examples of vinyl cyanide compounds include acrylonitrile and methacrylonitrile. The above monomers can be used alone or in combination of two or more. When graft polymerizing the monomer mixture to the rubbery polymer, there is a method in which emulsion polymerization is carried out by adding the monomer mixture to the rubbery polymer in a latex state. Any method commonly employed for producing the polymer may be used, such as a bulk-suspension polymerization method, a solution polymerization method, an emulsion-bulk polymerization method, etc. According to the impact-resistant resin composition of the present invention, the graft polymer contains 70 to 120 parts by weight of chemically bonded monomers to 100 parts by weight of the rubbery polymer;
The so-called graft rate is 70-120%, preferably 90
~110% is required. Furthermore, the intrinsic viscosity of the free aromatic vinyl compound/vinyl cyanide compound copolymer present as a matrix component in the resin composition in methyl ethyl ketone at 30°C is 0.65.
~0.80 is required. Graft rate is 70
% and/or when the above-mentioned intrinsic viscosity of the matrix component is less than 0.65, it becomes impossible to maintain the good vacuum formability and good strength when in contact with the polyurethane foam, which are the objectives of the present invention. . On the other hand, if the grafting ratio exceeds 120%, the rubbery polymer loses its rubbery properties and cannot be expected to exhibit desired strength. Moreover, if the intrinsic viscosity exceeds 0.80, it is not desirable because the fluidity during resin processing will be significantly reduced. Furthermore, the ratio of the aromatic vinyl compound to the vinyl cyanide compound in the rubber-reinforced resin composition of the present invention needs to be in the range of 2.3 to 3.0 in terms of weight ratio. If this ratio exceeds 3.0, good strength retention during contact with the polyurethane foam, which is the objective of the present invention, will not be achieved, and if it is less than 2.3, thermal stability during molding will deteriorate, which is undesirable. The graft polymer having the desired graft ratio shown above can be obtained by appropriately setting known polymerization conditions. For example, in the case of emulsion graft polymerization, a redox system of organic peroxide and iron salt is used as an initiator, and organic peroxides include cumene hydroperoxide, diisopropylbenzene hydroperoxide, paramenthane hydroperoxide, etc. The iron salt may be either a ferrous salt or a ferric salt, and sulfates and hydrochlorides are generally used. The amount of organic peroxide used may be 0.1 to 1.0 parts by weight, and the amount of iron salt used may be 0.001 to 0.1 parts by weight, based on 100 parts by weight of the polymerizable monomer. Any emulsifier used in normal emulsion polymerization can be used, but sodium or potassium salts of disproportionated rosin acid, hydrogenated rosin acid, etc. are generally used; 18 fatty acid salts can also be used. Further, if necessary, polymerization regulators are used, including mercapto compounds, such as usually long-chain mercaptans such as normal or tertiary dodecyl mercaptan, or dipentene, terpinolene, α-terpinene, and small amounts of other cyclic mercaptans. A terpene mixture consisting of terpenes is used, and the amount used is about 0 to 1.0 parts by weight. The polymerization temperature is preferably in the range of 40° to 95°C, and the polymerization temperature is 40°C.
If it is less than 95°C, the reaction will be difficult to proceed, and if it exceeds 95°C, the polymerization system will become unstable and a coagulum will tend to form. In addition to manufacturing by selecting appropriate polymerization conditions as described above, a method commonly practiced in this field is to prepare a graft polymer with a high rubbery polymer content in advance, and add an aromatic vinyl compound to this graft polymer. It is also possible to adopt a method of adjusting the content of the rubbery polymer by blending a copolymer with a vinyl cyanide compound. In this case as well, in order to achieve the purpose of the present invention, the rubber-reinforced resin composition finally obtained must satisfy the requirements of the present invention. In the present invention, by adding a diorganopolysiloxane and/or a fatty acid metal salt having a specific viscosity to the above resin composition as necessary, the excellent strength retention ability when in contact with the polyurethane foam is maximized. can be demonstrated. The diorganopolysiloxane used here is 25
The viscosity at °C is preferably in the range of 5 to 100,000 centistokes, preferably 5,000 to 50,000 centistokes. Organo substituents are also selected from the group consisting of alkyl, aryl and vinyl groups and combinations thereof. Two or more diorganopolysiloxanes can also be used in combination. The amount used is 0.01-2.0% by weight, preferably 0.05
About 1.0% by weight is preferable in order to achieve the purpose of the present invention. Fatty acid metal salts are metal salts of linear saturated fatty acids having 12 or more carbon atoms, such as lauric acid, palmitic acid, and stearic acid, and the metals include magnesium, calcium, strontium, barium,
Selected from zinc, cadmium, aluminum, tin, lead, etc. Two or more fatty acid metal salts can also be used in combination. The amount used is 0.1 to 3
The object of the present invention can be easily achieved when the amount is preferably 0.5 to 1.5% by weight. There is no particular restriction on the method of mixing the resin composition of the present invention and the above-mentioned additives, and a conventional mixing method may be employed. For example, a predetermined amount of both may be weighed and mixed using a Henschel mixer, tumbler, etc., or melt mixing may be performed using a hot roll, Banbury mixer, etc. Of course, when obtaining the resin composition in this way, stabilizers, colorants, and other additives can be added and blended as necessary. The present invention will be explained in detail below with reference to Examples.
The following examples use acrylonitrile-butadiene-styrene resin (hereinafter referred to as ABS resin) as a rubber-reinforced resin composition consisting of a rubbery polymer, a vinyl aromatic compound, and a vinyl cyanide compound component.
This is an example of performance evaluation when using . Powdered ABS resins of sample No. ~ shown in Table 1 were prepared by emulsion polymerization using a 10 glass reactor. The grafting ratio shown in Table 1 was measured by the following method. That is, a certain amount of powdered ABS resin (A) was poured into acetone to completely dissolve the free acrylolitrile-styrene copolymer, and the insoluble portion (B) was obtained from this solution using a centrifuge. . The grafting rate was calculated using the following formula. Grafting ratio = B - A × Rubber fraction in ABS resin / A × Rubber fraction in ABS resin × 100 Examples 1 to 3 Each of the powdered ABS resins of Sample No.
The mixture was melted and mixed in a 50 mmφ extruder to form pellets. The pellets obtained in this way are made into 1.5 mm thick and 40 mm wide extruders using a 40 mmφ extruder equipped with a T-die.
mm sheet. Width 5mm longer than this sheet
A 110 mm rectangular flat plate was cut out and used as a test piece for evaluating vacuum formability. This test piece was placed in a constant temperature chamber controlled at 180°C with a double-glazed front panel so that the inside could be observed, and only the upper end of the test piece was fixed with a clamp and hung vertically. The amount of sagging due to the test piece's own weight was determined by measuring the position of the lower end of the test piece, which was used as a measure of vacuum formability. This large amount of sagging means that the amount of sagging of the resin sheet becomes large during the sheet heating stage during vacuum forming processing. This is because the distance from the heating heater varies greatly depending on the location on the resin sheet surface, which increases heating unevenness.
If vacuum forming is performed in this state, the thickness of the molded product will vary greatly depending on its location. That is, a large amount of sagging of the resin sheet due to the test piece's own weight means that the thickness of the vacuum-formed product will vary widely depending on the location, which is not desirable. In addition, a rectangular flat plate with sides of 150 mm was prepared from the extruded sheet for the purpose of measuring the strength in contact with foamed polyurethane. This flat plate was prepared separately with a side of 150 mm and a depth of 30 mm.
Place the foamed polyurethane raw materials (PRG R x 510 [polyol] and TDI-TRC [isocyanate]) manufactured by Mitsui Nisso Urethane Co., Ltd. in the upper end of a rectangular hollow box with a bottom and mix in the hollow part with stirring at a ratio of 100:83.2. ) was injected and foamed. The thus obtained flat plate with foamed polyurethane adhered to one side was conditioned in a low temperature room at -30°C, and then the falling weight impact strength at this temperature was measured using a Dupont type falling weight impact tester. . In this measurement, the ABS resin sheet was fixed on the upper side, and a striking rod with a tip radius of 1/4 inch was used. Example 4 1.0 PHR of magnesium stearate was added to powdered ABS resin of sample No. and mixed with stirring using a Henschel mixer. The rest was the same as in Examples 1 to 3. Example 5 Evaluation was carried out in the same manner as in Example 4 except that aluminum stearate was used instead of magnesium stearate. Example 6 The procedure was the same as in Example 4 except that 0.2 PHR of polydimethylsiloxane (viscosity 10,000 centistokes) was added instead of magnesium stearate. Example 7 The procedure was the same as in Example 4 except that 0.2 PHR of polydimethylsiloxane (viscosity 10,000 centistokes) was further added. Comparative Examples 1 to 3 Sample No. 50 each of powdered ABS resin
The mixture was melt-mixed using a mmφ extruder to form pellets. The rest was the same as in Examples 1 to 3. Comparative Example 4 1.0 PHR of magnesium stearate was added to the powdered ABS resin of sample No. and mixed with stirring using a Henschel mixer. The rest was the same as in Examples 1 to 3. Comparative Example 5 Evaluation was carried out in the same manner as in Comparative Example 4, except that aluminum stearate was used instead of magnesium stearate. Comparative Example 6 The procedure was the same as in Comparative Example 4 except that 0.2 PHR of polydimethylsiloxane (viscosity 10,000 centistokes) was added instead of magnesium stearate. Comparative Example 7 The procedure was the same as in Comparative Example 4 except that 0.2 PHR of polydimethylsiloxane (viscosity 10,000 centistokes) was further added. The falling weight impact strength evaluation results of Examples 1 to 7 and Comparative Examples 1 to 7 are shown in Table 2. From the evaluation results shown in Table 2, it is clear that the resin composition according to the present invention has good vacuum moldability and exhibits good strength retention when in contact with foamed polyurethane.

【table】

[Table] Examples 8 to 11, Comparative Examples 8 to 11 ABS resins of sample No. shown in Table 3 were manufactured, and each was melt-mixed using a 50 mmφ extruder to form pellets. Thereafter, vacuum forming and falling weight impact strength were evaluated in the same manner as in Example 1. Display the results -
4. As shown in Comparative Example 10, when the grafting ratio is extremely high, or when the intrinsic viscosity of the matrix component is extremely high as in Comparative Example 11, moldability becomes extremely poor. As a result, the thickness of the sheet becomes non-uniform, resulting in poor vacuum formability, and the sheet becomes oriented, resulting in a decrease in falling weight impact strength. Furthermore, any one of the specified conditions of the present invention, such as the weight ratio of the aromatic vinyl compound and the vinyl cyanide compound, the intrinsic viscosity of the aromatic vinyl compound/vinyl cyanide compound copolymer of the matrix component, and the grafting ratio of the graft polymer, is satisfied. If even one of them comes off, as shown in the comparative example, both the vacuum formability and the falling weight impact strength are greatly reduced. That is, it is clear that only when the specified conditions of the present invention are satisfied, as shown in the examples, the resin composition has good vacuum formability and exhibits good strength retention when in contact with foamed polyurethane. .

【table】

【table】

Claims (1)

[Scope of Claims] 1. Consists of a graft polymer in which an aromatic vinyl compound and a vinyl cyanide compound are chemically bonded to a rubbery polymer, and an aromatic vinyl compound/vinyl cyanide compound copolymer, and is in contact with a polyurethane foam layer. In a rubber-reinforced resin composition used for manufacturing a vacuum-formed box, [] an aromatic vinyl compound and a 70~ of cyanide
120 parts by weight are chemically bonded, and [] the free aromatic vinyl compound/vinyl cyanide compound copolymer contained as a matrix component in the resin composition has an intrinsic viscosity of 0.65 to
0.80, [] The weight ratio of the aromatic vinyl compound to the vinyl cyanide compound in the resin composition is 2.3 to 3.0.
An impact-resistant resin composition characterized by being in the range of 2. A vacuum-formed box made of a graft polymer in which an aromatic vinyl compound and a vinyl cyanide compound are chemically bonded to a rubbery polymer, and an aromatic vinyl compound/vinyl cyanide compound copolymer, and in contact with a polyurethane foam layer. In the rubber-reinforced resin composition used for production, [] 70 to 70 parts by weight of an aromatic vinyl compound and a vinyl cyanide compound per 100 parts by weight of the rubbery polymer contained in the resin composition at a ratio of 10 to 30% by weight.
120 parts by weight are chemically bonded, and [] the free aromatic vinyl compound/vinyl cyanide compound copolymer contained as a matrix component in the resin composition has an intrinsic viscosity of 0.65 to
0.80, [] The weight ratio of the aromatic vinyl compound to the vinyl cyanide compound in the resin composition is 2.3 to 3.0.
[] 0.01 to 2.0% by weight of a diorganopolysiloxane having a viscosity of 5 to 100,000 centistokes at 25°C and/or 0.1 to 3% by weight of a fatty acid metal salt is added to the above resin composition. Impact resin composition.